Generally, the evaluation of compliance of wireless devices with respect to regulatory exposure limits is performed according to IEC 62209, IEEE 1528 or IEC/IEEE 63195 standards. At frequencies above 10 GHz, the relevant metric is near-field power density. Over The Air (OTA) test systems are becoming mandatory for testing such wireless devices due to the integrated millimeter sized antennas. OTA tests also include anechoic chambers in order to create test environments that closely simulate the conditions in which the devices will operate. For example, the document U.S. Pat. No. 10,110,326 B1 shows a multi-probe anechoic chamber OTA test system to perform radiated testing of 5G base stations and 5G user equipment.
However, due to beam-steering capability of 5G-NR devices that operate over the millimeter wave range, the near-field power density measurement requires to access a specific test mode in order to control the beams. The device can therefore be locked within a certain operating state with a certain beam direction, and near-field measurements are carried out at a defined grid in air near the device. The dependency on particular test modes results in the expense of network resources and further leads to a complex test system.
Accordingly, there is a need to provide a system and a method for near-field exposure measurements of a device under test, especially for evaluating near-field power density in a simplified manner without the necessity for specific test modes.